Method for the casting of large-size objects out of a high-viscosity concrete mix

ABSTRACT

The invention is concerned with a method and a mould in the casting of large-size concrete objects or corresponding elements for compacting high-viscosity casting mix. Thereat, the mould (3 or 17) comprises a bottom (8 or 24) and side walls (6, 7) as well as, additionally, a deck (9 or 25) for bringing the high-viscosity casting mix present in the mould (3 or 17) mechanically under pressure. According to the invention, repeated parallel dislocations back and forth are produced in the various regional zones of the mechanically pressurized high-viscosity casting mix (1) present in the mould (3 or 17), and in particular in parallel dislocation planes (2) of the casting mix. This is achieved by pivoting two opposite mould (3 or 17) walls (4, 5) or wall portions (20, 21, 22, 23) as synchronized and always in the same direction in relation to each other or in relation to their corresponding portions provided in pairs, which pivoting takes place around shafts (10, 11  or 28, 29) placed at a distance from one another, included in the planes of the said mould walls, and being parallel to each other and to the parallel dislocation planes (2) of the casting mix (1).

The present invention is concerned with a method in the casting oflarge-size concrete objects or corresponding elements for compactinghigh-viscosity mix. The invention also comprises a mould for carryingout the method, which mould comprises a bottom and side walls, as wellas, moreover, a deck for bringing the high-viscosity casting mix presentin the mould mechanically under pressure.

In prior art, it is known to compact the concrete mix by vibration, orto bring the concrete mix in the mould mechanically under pressure bypressing one wall of the mould against the concrete mix. Thereat, inconnection with the pressing action, the wall may additionally be variedbetween various angular positions. In prior art, it is also known tocast hollow slabs out of high-viscosity concrete mix by means of theslide-cast method. In such a case, the cavities of the hollow slab areformed by means of the slide-casting machine so that no thick wallstrengths remain in the slab. It is the presence of the cavities thatpermits the compacting of the high-viscosity concrete mix in the saidslide-cast method. On the contrary, in prior art it has not beenpossible to cast such massive concrete objects or elements whosesmallest dimension is also at least tens, possibly even hundreds ofmillimeters, out of a high-viscosity concrete mix (water/cement ratioabout 0.28 to 0.33).

It is an object of the present invention to permit the casting on siteof large-size concrete objects or corresponding elements out of ahigh-viscosity concrete mix, and the method in accordance with theinvention is mainly characterized in that repeated parallel dislocationsback and forth are produced in the various regional zones of themechanically pressurized high-viscosity casting mix present in themould, and in particular in parallel dislocation planes of the castingmix, by pivoting two opposite mould walls or wall portions assynchronized and always in the same direction in relation to each otheror in relation to their corresponding portions provided in pairs, whichpivoting takes place around shafts placed at a distance from oneanother, included in the planes of the said mould walls, and beingparallel to each other and to the parallel dislocation planes of thecasting mix.

The mould in accordance with the invention is mainly characterized inthat two opposite walls of the mould, or portions of these walls, havebeen fitted as synchronously pivotable always in the same direction inrelation to one another or to their corresponding portions provided inpairs, around shafts parallel to each other and included in the planesof the said walls.

The invention comes out more closely from the following description andfrom the attached drawing, wherein

FIG. 1 is a schematical presentation of the principle of the process ofcompacting of the concrete mix,

FIG. 2 illustrates the gliding of the thin lamellae or dislocationplanes of the concrete object to be compacted, in relation to each otherin a cubic cast piece, the lamellae being placed one above the other,

FIG. 3 is a schematical presentation of a casting mould as viewed fromabove,

FIG. 4 shows a section at A--A in FIG. 3, and

FIG. 5 shows a mould construction alternative for the mould shown inFIGS. 3 and 4, as a sectional side view.

In FIG. 1, it is assumed that the object to be compacted out ofhigh-viscosity concrete mix has the shape of a cube, shown in fulllines. In order that the high-viscosity concrete mix should be reallycompacted in all parts of the concrete object, in the concrete mix anefficient dislocation of all of the areas in the mix in relation to eachother must be produced throughout the entire object. According to theinvention, this is achieved so that the concrete mix is first broughtmechanically under pressure and that thereafter, in parallel dislocationplanes in the concrete mix, repeated parallel dislocations back andforth are produced by synchronously pivoting two opposite mould walls inrelation to each other. In FIG. 1, the paths of movement of the two wallplanes concerned are denoted with broken lines.

In order to illustrate the matter, in FIG. 2, the object 1 to becompacted is conceived as consisting of thin lamellae or dislocationplanes 2 placed one above the other. When the object 1 is, duringcompacting, shaped diagonally, the lamellae or dislocation planes 2glide in relation to each other. In FIG. 2, one extreme position of theworking is presented with full lines and the other extreme position withbroken lines. In the process of working, the frequency of oscillationmay be up to 10 to 20 oscillations back and forth per second,preferably, however, about 1 to 5 oscillations back and forth persecond. Therat, during the working, the lamellae or dislocation planes 2placed one above the other are sort of cut loose from each other asparallel dislocations, and this cutting proceeds through the wholeobject 1. Repeated shearing together with a pressure pressing the wallsof the object 1 produces compacting. In this connection, bringing thehigh-viscosity concrete mix mechanically under pressure means that acompression is caused in the concrete mix, e.g., by pressing the deckplane of the mould downwards. The presentation in FIG. 2 is, of course,only a presentation illustrating the process of compacting of thehigh-viscosity concrete mix. Of course, in practical performance, theside walls remain plane, i.e. it is assumed that the thickness of thelamellae is close to zero. Nevertheless, an efficient "shearing" of theconcrete mix takes place in the concrete object 1 to be compacted, inthe way described above, throughout the entire object.

FIGS. 3 and 4 show a mould for casting on site of large concrete objectsor elements and for compacting of high-viscosity concrete mix. The mould3 comprises a bottom 8, stationary side walls 6 and 7, as well as ahorizontal mould deck 9 movable in the vertical direction by means of acylinder-piston device 12. At the plane of the mould 3 bottom 8,pivotable walls or wall portions 4 and 5 of the mould 3 have beenmounted by means of horizontal shafts 10 and 11. The side walls or wallportions 4 and 5 of the mould 3, pivoting at their upper parts, are, bymeans of articulated joints 14 and 15, connected to a connecting rod 13,and to the other end of the connecting rod a horizontal cylinder-pistondevice 16 has been connected, by means of which, via the connecting rod13, synchronized back-and-forth pivoting movement of the pivotable sidewalls or wall portions 4 and 5 of the mould 3 is produced. Thus, theside walls or wall portions 4 and 5 pivot by means of thecylinder-piston device 16 and of the connecting rod 13 around the shafts10 and 11 in the way shown by broken lines in FIG. 4.

Thus, when the concrete object is being cast, the mould 3 is filled withthe high-viscosity concrete mix and the concrete mix is compressed fromabove by means of the mould deck 9 by pressing the deck downwards bymeans of the cylinder-piston device 12. Thereby the high-viscosityconcrete mix in the mould 3 is brought mechanically under pressure.Hereupon, repeated parallel dislocations back and forth are produced inthe parallel dislocation planes of the high-viscosity concrete mix bypivoting two opposite mould walls or wall portions 4 and 5 by means of acylinder-piston device 16 and of a connecting rod 13 around the shafts10 and 11 synchronously always in the same direction in relation to oneanother. The cylinder-piston device 12 presses the mould 3 deck 9 by auniform force, whereat a pressure is produced in the concrete to becompacted, e.g. about 0.5 to 1 bar. After sufficient compacting of theconcrete object has been achieved, the concrete is so rigid that thecast piece can be removed from the mould 3 immediately after thecompacting movement described above has been stopped.

FIG. 5 shows a mould construction alternative to that shown in FIGS. 3and 4. Therein, like in the embodiment of FIGS. 3 and 4, the mould 17has a bottom 24, two stationary walls at opposite sides of the mould 17,and the mould 17 deck 25. The mould 17 also has two opposite mobilewalls 18 and 19. The mobile walls 18 and 19 are pivotably mounted bymeans of shafts 26 and 27 to the plane of the bottom 24 of the mould 17,but, additionally, the walls 18 and 19 have been designed as folding atthe middle in relation to the articulated shafts 28 and 29. Thus, theside wall 18 consists of two wall portions 20 and 21, which can pivot inrelation to each other around the articulated shaft 28. Correspondingly,the side wall 19 consists of wall portions 22 and 23, which can pivot inrelation to each other around the articulated shaft 29. The articulatedshafts 28 and 29 have been connected to a connecting rod 30, ahorizontal cylinder-piston device 31 being connected to the other end ofthe said rod. In the embodiment shown in FIG. 5, the high-viscosityconcrete mix is brought mechanically under pressure by means of themould 17 deck 25 by pressing the deck 25 downwards by means of thecylinder-piston device 32. The compacting movement in the concrete mixis produced by means of the cylinder-piston device 31 by oscillating theparts 20 and 21 as well as 22 and 23 of the pivotable walls 18 and 19 ofthe mould 13 between the two extreme positions shown in FIG. 5. In thecompacting process, the angle of pivoting of the side walls or of theirparts is about 20° to 30°, i.e. the movement of pivoting of a side wallor its parts from the middle position to both sides is about 10° to 15°.

Of course, in the casting method in accordance with the presentinvention, the shape of the object to be compacted does not have to bethat of a cube or a rectangular prism, but many different alternativeshapes can be concerned. The faces of the object to be compacted mayalso be, e.g., curved faces. If the forms of the cast object to becompacted differ from plane faces, then, of course, the circumstancemust be taken into account that the forms of the object should notprevent efficient compacting as the side walls of the mould, or theirportions, are moved during the compacting action. In stead of concretemix, the casting mix may also consist of some other high-viscosity mixsuitable for the compacting method now concerned.

What is claimed is:
 1. A method in the casting of large-size concreteobjects or corresponding elements for compacting high-viscosity mix,wherein repeated parallel dislocations back and forth are provided invarious regional zones of the mechanically pressurized high-viscositycasting mix present in the mould, and in particular in paralleldislocation planes of the casting mix, by pivoting two opposite mouldwall portions in synchronization and always in the same direction inrelation to each other, said pivoting provided by a plurality of shaftsat a spaced distance from one another, said plurality of shaftspositioned in planes defined by said mould walls, and parallel to eachother and to the parallel dislocation planes of the casting mix.
 2. Amethod as claimed in claim 1, wherein the wall portions of the mould areoscillated at a frequency which is, at the maximum, 10 to 20oscillations per second.
 3. A method as claimed in claim 1, wherein thepivoting between extreme positions of the pivoting movement of the wallportions of the mould is about an angle of 20° to 30°.